website - How to proceed with a new OpenID user -

I am trying to find a way to deal with this situation.

- Original user - ID (primary key) email (unique) screen_name (unique)) - External user - OpenID_ID original-user_id

When an / Strong> When the user logs in, I have a new "root" user Do away I and Opanaidi account identifier before automatically create the new "original" user, I have some information Opanaidi name and try to get as email. If both existing users are "magical" registered, but if there are some of these fields, then they are presented to the user with the required form to fill the information.

OK, now I have a problem.

If a new user logs in to the openID user site, and openID gives me an email which has already been assigned to an existing user, how should I proceed ? (Keep in mind that email is a unique area of ​​my table)

1. Ask him to change the email stored in his system
2. Appoint this openID for me in the match Log in the database and the user as the same user is trying to log in with a different openID
3. Deny the login, even possibly the same user who is different Login with OpenID Defense is trying.
4. Login and warn the visitor that once entered, he has to appoint a new openID for his user. Personally, I think I should go for 4, as 1 person mistakenly viewed a new user for his second openID account without the path nº2 for me It is dangerous to say that the new openID matches the same user

   What do you think?

   PD: I have read this question: Anyone can create an OpenID account with an email in my account, which is already present in my system. But not 100% which I see.

Never select an option 2: Like you said, you do not want to reach the wrong person except It is up to you to decide whether to deny access or access, but ask the user to provide a different email address. I do not see much talk about denial of access because users can create a new open-end with another email address.